Hydrocarbon oil conversion



Feb. 5, 1935. J. D. SEGUY HYDROCARBON OIL CONVERSION Filed April 2'7,1931 JEAN DELATTRE SEGUY Patented Feb. 5, 1935 1 HYQROCARBON OILCONVERSION Jean Delattre Seguy, Chicago, Ill., assignor to Universal OilProducts Company, Chicago, 111., a corporation of South DakotaApplication April 27, 1931, Serial No. 533,103

8 Claims.

This invention relates to the treatment of hydrocarbon oils, and refersmore particularly to the conversion of relatively heavy oils and thesimultaneous'reconversion of various intermediate products from theprimary conversion.

The primary features of the invention provide an improved process andapparatus for the conversion of oils comprising a primary crackingsystem for the conversion of raw oil charging stock and utilizing aheating zone, a reaction zone and a fractionating zone consisting of aprimary and a secondary stage, a reduced pressure system for flashdistillation of the residual oil from the primary cracking systemcomprising a flash distilling chamber and a fractionator and a secondaryconversion system comprising a heating zone and a reaction zone in whichflash condensate from the fractionator of the reisduum flash distillingsystem and reflux condensate from .the secondary fractionating stage ofthe primary conversion system may besubjected to reeonversionconditions.

Reflux condensate from the first fractionating stage of the primaryconversion system is preferably returned to the heating element of thissame system for reeonversion, but may be supplied in part to the streamof heated oil discharging from the heating element of the seeondarycracking system for the purpose of cooling the heated products to thedesired temperature. Raw oil charging stock for the system may beintroduced all or in part into the heating element of the primarycracking system or may be supplied all or in part to the stream ofheated oil discharging from this same heating element being thereby, inthe latter case, subjected to relatively mild conversion conditions atthe same time cooling said stream of heated oil to a milder conversiontemperature than that employed in the heating element.

The various features of the present invention will be more apparent withreference to the attaclied diagrammatic drawing, which illustrates oneform of apparatus in which the process of the invention may bepracticed.

Referring more in detail to the drawing, raw

- oil charging stock may be supplied through line 1 and valve 2 to pump3, from which it may be fed through line 4 and valve 5 into heatingelement 6. The oil supplied'to heating element 6 which may be locatedwithin any suitable form of furnace '7 may be heated.to the desiredconversion temperature under any desired pressure conditions andpreferably under a substantial. superatmospheric pressure. The heated Ol may be discharged through line 8, valve 9 and line 10 into reactionchamber 11. If desired, all or any portion of the raw oil charging stockmay be diverted from line 4 and supplied through line 12 and valve 13 toline 10, commingling therein with 5 the stream of heated oil dischargingfrom heat-- ing element 6, serving to cool these products to a milderconversion temperature than that employed in the heating element and.being itself thereby heated to a relatively mild conversion temperature.

Chamber 11 is also preferably maintained un-- der.a substantialsuperatmospheric pressure and vapors may be separated from the residualoil in this zone.

The vapors may pass. through line 14 and valve 15 to fractionator 16which, as here illustrated, preferably comprises a primary fractionatingstage designated as 17 i and a second-' ary fractionating stagedesignated in the drawing as 18. The relatively heavy insuflicientlyconverted components of the vapors which may be condensed in zone 17 maypass through line 19 and valve 20 to pump 21 from which they may be fedall or in part through line 22, line 23 and valve 24 into line 4 andthence to heating element 6 for reeonversion.

The insufiiciently converted components of the fractionated vapors whichmay be condensed in zone 18 of the fractionator may collect upon tray ordeck 25 to be supplied therefrom to further treatment as will. be morefully described later. This fractionation is preferably so controlledthat the condensate thereof consists essentially ofpressure distillatebottoms. The relatively light desirable components of the fractionatedvapors may pass through line 26 and valve 27, may be subjected tocondensation and cooling in condenser 28, products from which may passthrough line 29 and valve 30 to be collected in receiver 31.Uncondensable gas may be released from the receiver tnrough line 32 andvalve 33 while distillate may be withdrawn through line 34 and valve 35.

Residual oil may be withdrawn from chamber 11 through line 36 and valve37 to chamber 38 which is preferably maintained under a substantiallyreduced pressure relative to that employed in chamber 11 and wherein theresidual oil may be further vaporized. Residual liquid remainingunvaporized in chamber 38 may be withdrawn therefrom to storage orelsewhere through line 39 and valve 40. Vapors evolved in chamber 38may, if desired, pass all or in part through line 41 and valve 42 intofractionator 43.

Reflux condensate from the upper portion or zone 18 of fractionator 16may be withdrawn through line 44 and valve 45 to pump 46. Likewisereflux condensate from fractionator 43 may be withdrawnthrough line 47and valve 48, passing thence through line 44 to pump 46. If desired, aportion or all of the vapors from chamber 38 may be diverted from line41, through line 49 and valve 50 into line 44 and thence to pump 46. Theoils thus supplied to pump 46 may be fed through line 51 and valve 52 toheating element 53, which may be located within any suitable form offurnace 54 and wherein the oil may be heated to the desired, conversiontemperature under any desired pressure conditions. Preferably, moresevere conversion conditions are employed in heating element 53 than.those utilized in heating element 6 and these conditions may be withinthe range of either liquid-vapor-phase or vapor-phase cracking. Theheated oil may be discharged from heating element 53 through line 55,valve 56 and line 57 into reaction chamber 58. If desired, a portion ofthe reflux condensate-from the lower portion of zone 17 of fractionator16 maybe supplied from line 22, by means of pump' 21, through line 59and valve 60 into line 57 commingling therein with the stream of heatedoil discharged from heating element 53, serving to cool these productsto a milder conversion temperature than that employed in heating element53, being itself heated to a somewhat milder conversion temperature thanthat em-- ployed in heating element 53 by direct contact with saidstream of heated products and passing therewith into chamber 58. Vaporsmay be separated from heavier products such as residual material and/orpolymerization products in chamber 58. The heavy products may bewithdrawn through 1ine'60 and valve 61, while the vapors may passthrough line 62 and valve 63 to be subjected to fractionation infractionator 43. It is thus evident that the recycle stock or refluxcondensate resulting from fractionation of the vapors produced in thesecondary system may be returned to the heating element of the samesystem for reconversion together with vapors from the residuum flashdistilling operation, and if desired, together with the refluxcondensate from the upper portion or zone 18 of fractionator 16. Insteadof going to fractionator 43, vapors from chamber 58 may go to a separatefractionating zone (not shown) from which vapors are separatelycondensed and collected, and reflux condensate returned to line 51 forrecracking in coil 53.

The relatively light desirable components of the vapors subjected tofractionation in fractionator- 43 may pass through line 64 and valve 85,may be subjected to condensation and cooling in condenser 66, productsfrom which may pass through line 67 and valve 68 into receiver .69.Uncondensable gas may be released from receiver 69 through line 70 andvalve 71. Distillate may be withdrawn from this receiver through line.72 and valve 73. The usual expedience of assisting fractionation andcontrolling the outlet temperature oi.v the vapors from any K or all ofthe fractionating zones of'the system such as, fo example, supplyingdistillate from receiver 31 and/or from receiver 69 to fractionator 43and/or fractionator 16, by well known means, may be employed althoughnot here illustrated.

Pressures employed within the system may maybe utilized between any ofthe various elements. Preferably, a substantially reduced pressurerelative to that employed in the primary cracking system is utilized inthe residuum flash distilling system, while the secondary crackingsystem may utilize substantially the same, higher or lower pressure thanthat employed in the pri mary cracking system, depending upon thecharacter of the distillate cracked therein as well as the resultsdesired. Conversion temperatures employed may range from 800 to 1200 F.,more or less. The pressures employed in the conversion zone arepreferably of the order of to 1,000 pounds per square inch, and thepreferred temperatures may range from 850 to 950 F. in this zone. Theparticular conditions employed will depend on the charging stocks aswell as upon the results desired.

As a specific example of operating conditions of which, together withreflux condensate from the primary fractionating stage, is-subjected inthe heating element of the primary cracking system to a conversiontemperature of approximately 930 F. under a superatmospheric pressure ofapproximately 275 pounds per square inch. The temperature of the streamof heated oil from this heating element is reduced to ,approximately 900F. prior to its introduction into the reaction chamber by supplying aportion of the raw oil charging stock directly into the stream of heatedproducts. The reaction chamber of the primary cracking system is alsomaintained under a superatmospheric pressure of approximately 275 poundsper square inch but is reduced in the flash distilling chamber toapproximately 30 pounds per square inch. Reflux condensate from theupper or secondary fractionating stage, reflux condensate from thefractionator of the sec ondary cracking system and substantially all ofthe gasoline-free vapors from the flash distillation of the residual oilare subjected to a temperature of approximately 1,000 FL, under asuperatmospheric pressure of about 60 pounds per square inch in theheating element of the secondary cracking system. A sufficient quantityof reflux condensate from the lower or primary fractionating zone isintroduced into the stream of heated oil from the heating element of thesecondary cracking system to cool this material to a temperature ofapproximately 950 F. prior to its introduction into the reaction chamberof the secondary system.

' This operation may yield approximately 62% of motor fuel having ananti-knock value ap- I non-vaporous residue, the vapors subjected tofractionation to produce a light fraction, an in-, termediate fractionand a heavy fraction, the heavy fraction being returned to the heatingzone for retreatment, and the non-vaporous residue being discharged intoa reduced pressure zone where latent heat vaporization takes place, theimprovement which'comprises admixing controlled amounts of theintermediate fraction from the fractionation with constituents vaporizedin said reduced pressure zone of latent heat vaporization, subjectingsaid mixture to vapor phase cracking conditions, separating the lighterconstituents of said vapor phase cracking from the heavier constituents,fractionating the lighter constituents and returning regulatedquantities of the reflux condensate formed in said latter fractionationto the vapor phase cracking zone for retreatment.

2. A process such as claimed in claim 1 characterized in that regulatedportions of the heavy fraction separated in the primary fractionationare diverted and admixed with the heated mass passing from the vaporphase cracking zone to the separating zone.

3. A process such as claimed in claim 1 characterized in that the vaporsseparated in the zone of reduced pressure are subjected to fractionationin the same zone as the vapors from the vapor phase cracking.

4. A process such as claimed in claim 1 wherein the conditions offractionation are so controlled that the intermediate fraction consistsessentially of pressure distillate bottoms.

5. A hydrocarbon oil cracking process which comprises subjecting the oilto cracking conditions of temperature and pressure in a primary crackingzone, separating the oil into vapors and unvaporized oil, subjecting thevapors to primary and secondary dephlegmation, returning resultantprimary reflux condensate to the cracking zone for retreatment therein,flash distilling the unvaporized oil by pressure reduction and combiningresultant flashed fractions with secondary reflux condensate formed bysaid secondary dephlegmation, supplying the mixture to a second crackingzone and cracking the same therein at higher temperature than ismaintained on the oil in the primary cracking zone.

6. A hydrocarbon oil cracking process which comprises subjecting the oilto cracking conditions of temperature and pressure in a primary crackingzone, separatingthe oil into vapors and unvaporized oil, subjecting thevapors to primary and secondary dephlegmation, returning resultantprimary reflux condensate to the cracking zone for retreatment therein,flash distilling the unvaporized oil by pressure reduction,dephlegmating the flashed vapors and combining resultant refluxcondensate with secondary reflux condensate formed by said secondarydephlegmation, supplying the mixture to a second cracking zone andcracking the same therein at higher temperature than is maintained onthe oil in the primary cracking zone.

7. A hydrocarbon oil cracking process which comprises subjecting the oilto cracking conditions of temperature and pressure in a primary crackingzone, separating the oil into vapors and unvaporized oil, subjecting thevapors to primary and secondary dephlegmation, returning resultantprimary reflux condensate to the cracking zone for retreatment therein,flash distilling the unvaporized oil by pressure reduction, combiningthe flashed vapors with secondary reflux condensate formed by saidsecondary dephlegmation, supplying the resultant mixture to a secondcracking zone and cracking the same therein at vapor phase crackingtemperature.

8. A hydrocarbon oil cracking process which comprises subjecting the oilto cracking conditions of temperature and pressure in a primary crackingzone, separating the oil into vapors and unvaporized oil, subjecting thevapors to primary and secondary dephlegmation, returning resultantprimary reflux condensate to the cracking zone for retreatment therein,flash distilling the unvaporized oil by pressure reduction,dephlegmating the flashed vapors and combining resultant refluxcondensate with secondary reflux condensate formed by said secondarydephlegmation, supplying the mixture to a second cracking zone andcracking the same therein at higher temperature than is maintained onthe oil in the primary cracking zone, and combining the cracked vaporsfrom the second cracking zone with the flashed vapors undergoingdephlegmation whereby the heavier fractions of said cracked vapors arereturned as reflux to the second cracking zone in said mixture.

JEAN DELATTRE SEGUY.

